I bought a crappy little spl meter at wal mart and gave it a run. I have a single rlp dual 4 runnin at 2 ohms and 800 watts. I played a 50 hz test tone and it hit 129.2 db at the dash. I have no sound deadener or anything yet. Is that a good reading? And how long do you play a test tone in a comp for spl? Im just wonering how loud it can get. I would imagine i could get at least 130 out of it.....I just dont know.

Seems low, but not surprised in that a crappy spl meter won't be able to measure chit at 50hz.

I metered a pair of RL-p 12"s sealed off an rf 800@2 from a trunk car that was gutted. no rear seat or trunk carpet or anything other then front seats and headliner/main floor carpet. he did a best of 133.2 on my new TL mic. I don't think it was optimum to be sealed, and IF I were to of tested his car I'd of been able to get it louder for sure... I like ported though cabin gain can do wonders... so if that were a sealed box I don't see how much louder it'd go on a real spl sensor, without testing moving the box around and other things can gain spl at a given location say dash

now is it better to have the box closer to the back or front of the trunk? Is there any average gain on spl with the addition of good sound deadener? I am going to use second skin sludge and damplifier on the doors and trunk.

now is it better to have the box closer to the back or front of the trunk? Is there any average gain on spl with the addition of good sound deadener? I am going to use second skin sludge and damplifier on the doors and trunk.

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in many cars, facing the sub straight to the back of the car, and having it positioned in the back of the trunk brings the best SPL gains.

As far as average gains on spl goes, its very hard to say, since decibels are measured exponentially. a 1db gain in the 140s means worlds, whereas a 1db gain in the 120s would be far less remarkable. You will definitely hear a difference as far as sound reproduction goes. less outside noise coming in, more sound staying in.

If you really want good results from your deadening, don't waste your time with second skin sludge, as I did. I thought thicker = better dampening, but apparently not. Anthony from second skin told me that regular Spectrum is harder to put on, but yields far better results, and Spectrum Firewall is their best liquid dampener. So unless you want the ease of application that Sludge gives you, but want to sacrifice functionality, you might want to change your order.

I have a feeling sean is right, a cheaper meter might have difficulty measuring a single low note.

It will measure them, but the response will roll off just like if you try to play high notes out of a sub. If it is a Class II meter (which unless you spend upwards of $1500 it is at best) it will not at all measure accurately down at the 50hz region. It might be repeatable but that has nothing to do with accuracy if the transducer is rolling off so fast.

2 RL-p 12s off of 1200 watts in a sealed box, in a single cab truck...USACi Style mic in the kick 141.0 at 41 Hz.

Sure you didnt just max out the meter? i have a radio shack meter and it maxes out at 129.x and is extremely inacurate and can only 1/2 measure acuratly below 100Hz in C weighting.

ever seen a real anecho responce graph this spikey?

Nice dynamic range on those SPL meters, 129dB ha, didn't actually think of that. NOBODY in industry will use them to measure anything as they are pretty much crap.

CB what is the plot above? And when you say anechoic response, you must have one heck of a room to measure below 40Hz. In fact, it would have to be bigger than any anechoic chamber I have ever heard of. They can have some weird-azz gain in the low frequencies....

well, open 5 acre feild beind a plywood windscreen

good enough for a 9th grade science project.

Ah, free field...